British Pat. No. 1,357,633 describes interalia compounds of the formula (I): ##STR2## and salts thereof wherein A.sub.1 is an alkylene group of 2-4 carbon atoms; A.sub.2 is a hydrogen atom or a C.sub.1-4 alkyl group and A.sub.3 is a hydrogen atom or a C.sub.1-4 alkyl group. These compounds were described as possessing activity on the central nervous system. However it is now believed that the compounds of the formula (I) are not sufficiently potent as use as anti-depressants. There has now been discovered a group of compounds which have more potent mood modifying activity than the compounds of the formula (I) and which at higher doses have the additional utility of suppressing appetite.